This invention relates to universal joints of the type in which two rotary members are connected by furcations pivotally connected in transverse planes to the trunnions of a journal cross member. Generally, the furcations of the members are provided with radially extending aligned openings in which the trunnions of the journal cross member are positioned. Interposed between the trunnions and the furcations are cup-shaped bearing races, the peripheries of which engage the furcations. Each race contains an annulus of needle bearings interposed between the inner periphery thereof and its associated trunnion, so that substantially frictionless movement may take place between the trunnion and the bearing race.
More particularly, this invention is directed to sealing means for the opening between the end of each bearing race and trunnion so that lubricant is retained within the bearing race, and dirt and foreign matter is excluded from same.
Prior art means for sealing the junction of bearing race and trunnion have taken many forms. The earliest constructions were merely metallic elements which fixedly engaged either the trunnion or the bearing race and slidingly engaged the other. However, due to accumulation of tolerances, and as a result of wear, such a seal did not always make adequate contact with the race or trunnion member so that a less than satisfactory result was obtained. Later developments in the art included a resilient element formed to engage the trunnion and also to engage the radially inner end of the bearing race. This type of seal, however, did not perform satisfactorily because the resilient sealing means soon became brittle and deteriorated after wear and exposure to elements of contamination.
Later developments in the art evolved a resilient sealing member for engaging either one of or both the trunnion and the bearing race, and included a metallic portion which overlayed the resilient member to compress same between the bearing race and trunnion. However, the majority of these seals only engaged the bearing race on the radially inner end thereof, so that an unsatisfactory sealing condition continued to persist.
In still later prior art seals, the resilient portion of the seal was adapted to engage both the inner and outer peripheries of the bearing race in addition to the metallic portion of the seal engaging the trunnion of the journal cross. Such construction resulted in a better sealing relationship; however, several problems were still prevalent. For example, the metallic portion of the seal did not properly secure the engagement of the resilient material with both the inner and outer peripheries of the race. Additionally, as the seal projected within the bearing race, there was a tendency for the annulus of needle bearings contained therein to abut the resilient material, and to therefore be subjected to objectionable frictional drag. This required the addition of a separate metallic element disposed interjacent the resilient material of the seal and needle bearings to reduce the latter drag.
Although much effort has been directed toward the enhancement of universal joint bearing seals, particularly as to the quality of internal sealing means relative to the bearing race, there remained a need for greater external protection from contaminating elements. Thus, an improved external sealing means was desired for the protection of the universal joint portions in direct contact with dirt, moisture, and other elements of contamination.